This is not very much obfuscated, but on the other hand, it can adapt itself to your own configuration...

use CGI;@ARGV=grep{-e}map{"$_/CGI.pm"}@INC;$t=join'',map{chomp;$_}<>;%
+c=qw/
2.42  11628;2324;30658;2060;22472;16482;
2.46  11926;2386;31338;2119;23033;16933;
2.49  12067;2410;31706;2136;23294;17122;
2.56  13145;2535;33058;2258;24538;18297;
2.74  12378;2435;32675;2155;23993;17625;
2.753 12523;2462;33017;2179;24257;17849;
/;$c=$CGI::VERSION;map{$n{$_}++}(/(....)/g)for+map{substr$t,$_}0..3;@n
+=sort
keys%n;printf$c{$c}?"%s"x6:"Please, retry with this line:\n$CGI::VERSI
+ON ".
"%s;"x6,@n[split/;/,$c{$c}],(grep{$_[$_]=~/Just| ano|ther| Per|l ha|ck
+er/}+
map{$_[$i]=$_;$i++}@n)[2,1,5,0,4,3]
[download]

CGI was the biggest module I could find in the standard Perl distribution, so I could be sure it would have what I needed. chomp is used for portability reasons. I hope this work on Macs too.

Note: If someone can find a core module that hasn't changed in the last two or three years, I am very interested! :-)

Update: I tested the script on several installs, I now have 3 different lines for CGI version 2.56. I am afraid that CGI is quite different between platforms, installs and distributions... :-(

Other lines that might work for you:

2.46  11925;2386;31335;2119;23030;16931;
2.56  13142;2534;33055;2257;24535;18294;
2.56  13144;2536;33058;2259;24536;18296;

So If you don't get the expected result, remove the line corresponding to your CGI version.